Fluid blast circuit interrupter



y 1959 H. N. SCHNEIDER 2,897,324

FLUID BLAST CIRCUIT INTERRUPTER Filed Oct. 9, 195'? Inventor:

I Harold N. Sc -rweiciexr,

by m His I ttorney.

United States Patent FLUID BLAST CIRCUIT INTERRUPTER Harold N. SchneidenSpi'ingfield;Pa., as'signor to General Electric Companyya' corp'oration'of New York Application October 9, .1957, Serial No. 689,122

7 Claims. =(Cl. 203- 148) This invention relatesto a'circuitiinterrupter which relies upon a fluid blast for extinguishing acircuit-interrupting arc and, more particularly, to an arrangement forholding the arc in a desired position for eflicient interruption and forpreventing the fluidblast fromdriving the are into a position where thevarc might damage relatively vulnerable parts of the interrupter.

-In many fluid blast circuit interrupters, the are extinguishing blastwhich is directed into the arc tends to drive one terminal of the areconsiderable distances downstream from its original position. If thedisplaced arc terminal happens to be driven into proximity with arelatively vulnerable part of the interrupter, the arc can, of course,cause material damage to the interrupter.

This problem is of particular importance in the pressurized type ofinterrupter which has its blast-controlling valve located downstreamfrom the arcing contacts of the interrupter. In such designs, if the arcterminal happens to be driven onto the blast valve, the blast valvecould be damaged and the operation of theinterrupter, thus, impaired.

For limiting the movement of an arc terminal, it has been customary toprovide a downstream probe to which the arc terminal can readily attach.Prior probes, however, have not been entirely reliable in preventing thefluid blast from driving the arc terminal off of the probe and furtherdownstream.

Accordingly, an object of my invention is to provide a downstream probewhich is highly effective in anchoring the arc terminal in positionagainst the on-rushing fluid blast.

In carrying out my invention inone form, I provide a fluid blast circuitinterrupter which'has a'pair of separable contacts for establishing acircuit-interrupting arc. For extinguishing the arc, a blast of fluid isdirected into the arc, and this blast is exhausted through a conductiveexhaust member defining an exhaust passage downstream from said arc.Projecting from a wallof said passageway transversely into the path ofsaid blast is a conductive probe of arc-resistant material. The probehas an upstream surface of a non-streamlined configuration for coactingwith said blast to form upstream from said surface a stagnation regionof sufficient volume to encompass a substantial portion of a terminal ofthe arc. When the blast, during the arc-extinguishing process, acts todrive the are into the region of the probe, one terminal of the arc iscaptured Within this stagnation region and further downstream motion ofthe terminal is thereby prevented.

For a better understanding of my invention reference may be had to thefollowing specification taken in conjunction with the accompanyingdrawing wherein:

Fig. 1 is a cross-sectional view of a fluid blast circuit interrupterembodying my invention.

Fig. 2 is an enlarged perspective view of one of the components of Fig.1, and

Fig. 3 is an enlarged side elevational view of the components shown inFig. 2.

2,897,324 Patented July 28, 1959 Referring now'to Fig. 1,t-he circuitinterrupter-shown therein is of the"sustained-pressure, ga's blast 'typedescribed and claimed in US. Patent No. 2,783,338, -Beatty, assigned-tothe assignee ofthe present invention. Oniy those parts'of the Beattyinterrupter which are considered necessary'to provide anunderstanding ofthe present-invention have been shown in Fig. 1. In this regard, onlythe top portion of 'the'interrupter has been showninasmuch as theinterrupter is generally symmetrical with respect to a horizontal planeand the bottom portion is substantially'identical to the top portion. Asdescribed in detail in-the Beatty patent, the interrupter comprises acasing'12 which isnormallyfilled with pressurized gas to defineaninterruptingchamber 11. Located within the interrupting chamber 11 area pair of relatively movable contacts 14 and '16 which can be separatedto draw a circuit-interruptingarc within the pressurized gasof thechamber 11. The contact 14 is relatively stationary, whereas the othercontact 16' is mounted for pivotal movement about afixed'current-carrying pivot 18. Wheat-he contact '16 is drivencounterclockwise about the'pivot 18, an arc is established intheregionwhere the contacts'pa'rt. The movable contact 16 is shown in'Fig. 1inapartially open position through which it passesduring acircuitinterrupting operation.

The movable contact 16 issupportedby means-of its current carrying pivot'18 on a conductive bracket 19 which is preferably formed' integral"with a stationary cylinder 32. The cylinder 32' at its left hand "endissuitably supported from' a'generally cylindrical casting 33. The casting33 at its left' hand end has an annular-flange 34 suitably secured to' amating flange 35 rigidly carried by the stationary metallic casing 12.

"For producing a gas' blast to aidin extinguishing the arc, thecylindrical casting'33 contains a normally clos'ed exhaust passageway'36'leading from"the interrupting chamber 11 to'the surroundingatmosphere. The exhaust member 33 at its right hand end is provided witha nozzle type electrode 38 defining an inlet orifice tothe exhaustpassage 36. The'flow of 'arc-extinguishinggas"through the nozzleelectrode 38 and the exhaust passage 36 is'controlled bymeans of acylindricallyeshaped reciprocable blast valve member40 located at theouter end of the exhaust passage 36. Thisblast valve"member"40'normallyoccupies a closed position wherein an annular flange 42 formed at its"left hand end :se'alin'gly abuts against the stationary flange 34, whichserves as a'valve seat. In the position of 'Fig. 1, however, the valvemem ber 40 is shown in a' partially open position through which itpasses during a circuit-interruptingoperation. Opening of the valvemember 40 allows pressurized gas in the chamber 11 to flow at high speedthrough the nozzle 38 and out the passageway 36 past the valve. member40 to atmosphere, as indicated by the arrows in Fig. 1. The manner inwhich this gas blast acts to extinguish the arc will soon be describedin greater detail.

At its right hand end, the cylindrical valve member 40 surrounds aprojecting support v41 upon which the valve member 40 is smoothlyslidable. This support 41 is shown formed-integral with the casting 33.A compression .spring44positioned.between the valve member 41) and thesupport 41 tends to hold the valve member' ltl in its closed positionagainst the flange 34.

.To protect the support 41 and the right hand end of the valve member-40from the harmful effects of arcing, a protective metallic tube43 ispositioned about these parts and is secured to'the support 41 bysuitable fastening means, such as 44a. Secured to "the outer surface ofthis tube 43 is a probe 45 which projects radially from the tube 43. andtransversely into the path of the fluid blast. flowing through thepassageway 36. As .will

'soon appear more clearly, the lower terminal of the arc is transferredto this probe 45, and, for this reason, the probe is preferably composedof a refractory conductive material which is highly resistant to arcing.Preferably, the probe comprises a base portion 46 which is formedintegral with a body portion 47 of the probe. The upstream surface 48 ofthe probe faces the fluid blast and is of a non-streamlinedconfiguration with respect to the fluid blast and, as a result, coactswith the blast to form a relatively large stagnation region 49 upstreamfrom the surface 48. The stagnation region 49 is best shown in Fig. 3where the streamlines representing the approximate flow pattern past theprobe are shown. The innermost streamline is spaced by an appreciabledistance from the adjacent surfaces of the probe, and this interveningspace constitutes the stagnation region. In this region of stagnation,most of the flow which is present is believed to be in the form ofeddies having little or no velocity in the general direction of thefluid blast. The manner in which this stagnation region is utilized willsoon appear more clearly.

For controlling the operation of the blast valve 40 and the movablecontact 16, a combined operating mechanism 50 is provided. Thismechanism 50 is preferably constructed in the manner disclosed andclaimed in the aforementioned Beatty patent, and its details form nopart of the present invention. Generally speaking, this mechanism 50comprises a valve-controlling piston 51 and a contact-controlling piston52 mounted within the cylinder 32. The valve-controlling piston 51 iscoupled to the valve member 40 through a piston rod 54 suitably clampedto the valve member 40. The contact-controlling piston 52, on the otherhand, is connected to the movable contact 16 through a piston rod 58 anda cross head 59 secured to the piston rod. A link 60 pivotally joined tothe cross head at 61 and to the movable contact at 62 interconnects thecross head and the movable contacts 16. When the valve-controllingpiston 51 is driven to the right, it acts to open the valve member 40and, simultaneously, to drive the contact-controlling piston 52 to theright to produce opening movement of the contact member 16.

Opening movement of the contact member 16 first establishes an arebetween the ends of contacts 14 and 16. The blast of air which isflowing through the nozzle 38, however, quickly forces the upperterminal of the arc on to an arcing electrode 70, which is electricallyconnected to the stationary contact 14. As opening motion of the movablecontact 16 continues, the gas blast forces the lower terminal of the arcto transfer from the contact 16 to the orifice of nozzle 33 and thenimpels this lower terminal into the orifice and on to the right hand endof the protective tube 43. From there, the fluid blast drives the lowerarc terminal to the left and into the previously described stagnationregion 49 adjacent the non-streamlined upstream surface 48.

In accordance with my invention, this upstream surface 48 is of such asize and configuration that the stagnation region 49 is of suflicientvolume to encompass a substantial, and preferably a major, portion ofthe arc terminal. As a result, the arc terminal is, in effect, shieldedfrom the high velocity flow of the fluid blast and remains effectivelyanchored to the probe within the stagnation region in spite of theblast. The approximate position of the arc during this interval is shownat 71 in Fig. 1. When the arc has moved into this approximate position,the action of the gas blast becomes effective to deionize and extinguishthe arc, thereby interrupting the circuit. The position of the probe isso selected that the are, when attached to the probe, is subjected to across-blast, as well as an axial blast, and this materially facilitatesthe interrupting process. In this regard, note particularly that theportion of the are which is located adjacent the probe is disposedtransverse to the general direction of the blast flowing through the ,4nozzle 38. Additionally, the position selected for the probe is such asto provide a minimum length of are consistent with preserving thedesired flow pattern through the orifice of the nozzle 38 and withrespect to the arc itself.

Since the probe acts, as above-described, to prevent the arc terminalfrom being driven further downstream, the possibility that the arc willbe driven into proximity with the blast valve 40 is effectivelyprevented. Correspondingly, the possibility that the blast valve will bedamaged by the arc and the operation of the interrupter thereby impairedis effectively prevented.

Although I have shown the upstream surface 48 as being of a planarconfiguration disposed generally perpendicular to the direction of theblast, it will be apparent that certain minor variations can be made inthe nonstreamlined configuration of the surface. For example, thissurface can be slightly concave with respect to the direction of theblast. In any case, however, the surface should be of a non-streamlinedconfiguration and capable of producing a stagnation region of suflicientvolume to encompass a substantial and preferably a major portion of thearc terminal. Streamlined upstream surfaces, such as those of a roundedconfiguration, convex with respect to the direction of the blast, havebeen found ineffective to provide such a stagnation region.

The purpose of the base portion 46 of the probe is to providearc-resistant material in the immediate vicinity of the anchored arcterminal so as to prevent the are from causing any damage in thisregion. The upper surface of this base portion is transversely-disposedwith respect to the position occupied by the axis of the lower portionof the are when the arc terminal is located within the stagnation region49. Preferably, the base 46 has its upstream end tapered at 65 so as tofacilitate movement of the arc terminal on to the probe and to preventretardation in the motion of the terminal just ahead of this point.

With respect to the arcing electrode 70 for the upper arc terminal, itwill be noted that a centrally-disposed passageway 72 is providedtherein. One of the purposes of this passageway is to encourage motionof the upper arc-terminal on this electrode by denying the arc terminala possibly-stable footing at the center of the electrode. Thismaterially aids in reducing erosion of the electrode 70 due to arcing.

While I have shown and described a particular embodiment of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from myinvention in its broader aspects and I, therefore, intend in theappended claims to cover all such changes and modifications as fallwithin the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a fluid blast circuit interrupter, a pair of separable contactsfor establishing a circuit-interrupting are, means for causing a blastof arc-extinguishing fluid to be directed into said arc, a conductiveexhaust member electrically connected to one of said contacts anddefining downstream from said are a passageway for said fluid blast, aconductive probe of arc-resistant refractory material projecting from awall of said passageway transversely into the path of fluid flowingthrough said passageway, said probe having an upstream surface ofnonstreamlined configuration facing the fluid blast for coacting withsaid fluid blast to form upstream from said surface a stagnation regionof suflicient volume to encompass a substantial portion of the terminalof said arc, said fluid blast acting to drive one terminal of said arefrom one of said contacts onto said probe and into captured relationshipwithin said stagnation region.

2. The fluid blast circuit interrupter of claim 1 in which said probe isso located that when said arc terminal is captured within saidstagnation region, the portion of 0 said arc adjacent said probe issubjected to a cross-blast by said fluid blast.

3. The combination of claim 1 in which said probe also comprises a baseportion having a surface extending upstream from said upstream surfacetransverse to the axis of an adjacent portion of said are when the arcterminal is located within said stagnation region.

4. In a fluid blast circuit interrupter, a pair of separable contactsfor establishing a circuit-interrupting arc, means for causing a blastof arc-extinguishing fluid to be directed into said arc, a conductiveexhaust member electrically connected to one of said contacts anddefining downstream from said are a passageway for said fluid blast, aconductive probe of arc-resistant refractory material projecting from awall of said passageway transversely into the path of fluid flowingthrough said passageway, said probe having a generally planar upstreamsurface disposed generally perpendicular to the direction of said blastin the immediate region of said surface for coacting with said blast toform thereadjacent a region of low velocity in comparison to the blastvelocity, said blast acting to drive one terminal portion of said arefrom one of said contacts onto said probe and into captured relationshipwithin said region of low velocity.

5. In a fluid blast circuit breaker, means forming a pressurizedinterrupting chamber, a pair of separable contacts mounted in saidchamber for establishing a circuitinterrupting are, a conductive exhaustmember electrically connected to one of said contacts and defining apassageway leading from the region of said contacts to a low pressureregion outside of said interrupting chamber,

means including a movable blast valve member located within saidpassageway downstream from said contacts for producing a fluid blastthrough said passageway upon opening of said valve member, a protectivetube surrounding said movable blast valve member at an upstream sidethereof and forming a wall of said passageway, a conductive probe of areresistant material projecting from said tube transversely into the pathof fluid flowing through said passageway, said probe having an upstreamsurface of non-streamline configuration facing said fluid blast forcoacting with said fluid blast to form upstream from said surface astagnation region of sufficient volume to encompass a substantialportion of a terminal of said arc, said fluid blast acting to drive oneterminal of said arc onto said probe and into captured relationshipwithin said stagnation region.

6. The combination of claim 5 in which said upstream surface is of agenerally planar configuration and is disposed generally perpendicularto the direction of said blast.

7. The combination of claim 5 in which said probe also comprises a baseportion having a surface extending upstream from said upstream surfacetransversely with respect to the axis of an adjacent portion of said arewhen the arc terminal is located within said stagnation region.

References Cited in the file of this patent UNITED STATES PATENTS2,570,610 Taylor Oct. 9, 1951 2,574,334 Latour Nov. 6, 1951 2,783,338Beatty Feb. 26, 1957

